At a pipeline fuel terminal operated by Chevron Corporation, a malfunction in a valve header allowed several thousand gallons of diesel to enter the site’s emergency spill retention basin. Once the diesel was recovered from the basin, it was discovered that diesel had leaked from the basin and was partially trapped between the basin liner and the earthen floor of the retaining basin. We mounted an effort to vacuum extract diesel from perforations made in the basin liner, investigated and found the leaking seem that allowed diesel to leak from the liner, and worked with a contractor to repair the liner. We also conducted an investigation to delineate the extent of diesel impact to soil and groundwater, and initiated remediation to remove diesel from strategically placed extraction wells. Recovered diesel was sent back to the refinery as transmix for recycling.